In the operation of an earthmoving vehicle such as an excavator, it is a common occurrence to encounter different types of materials and digging conditions. As a result, specialized buckets have been designed to be utilized in a specific type of soil or for a specific type of digging operation. Therefore it is not uncommon for an operator of an excavator to switch from one bucket to another to perform a variety of operations.
The excavator bucket linkage commonly includes a support arm or stick, and a bucket rotation linkage that is mounted to the stick. The bucket is mounted at one point to the stick and at another point to the rotation linkage. A pair of pivot pin assemblies are positioned within aligned bores formed between the bucket and excavator linkage at each mounting point. The pin assemblies are mounted within their respective bores with an interference fit or press fit. Removal and replacement of the pin assemblies requires a good deal of time and specialized equipment in most instances. Therefore frequent changes between work implements can be very costly in terms of machine down time. On the other hand, if an implement is not changed because of the time required to do so, the work efficiency of the machine is sacrificed.
To alleviate the aforementioned problem, quick-disconnect mountings of various types have been developed. While many of the current designs function to quickly connect and disconnect the various types of implements to an excavator linkage, their construction has created a compromise in the work efficiency of the implement. In some instances, as in U.S. Pat. No. 4,187,050 issued on Feb. 5, 1980 to Gail G. Barbee and assigned to the assignee of the subject application, an adapting bracket is connected to the excavator linkage where a conventional implement such as a bucket would normally be attached The bracket is provided with a connecting arrangement that engages a number of work implements that have been specifically designed for attachment to the bracket. This results in an alteration in the geometry of the excavator linkage. Since the bucket is no longer connected directly to the stick, its point of rotation, or tipping radius, about its connection to the mounting bracket is offset from that of a conventional bucket. The geometry of the bucket linkage is specifically calculated to apply the optimum force available from an actuating cylinder to the tip of the bucket where the teeth will penetrate the earth. Movement of the point of bucket rotation upsets this condition and the amount of digging force applied to the bucket is greatly reduced.
Other so-called "quick coupling" devices require the use of a bracket assembly that have a pair of upstanding sidewalls that extend between the end of the stick and the bucket rotation linkage. Pivot pins extend through bores in the end of the stick and rotation linkage to mount the bracket assembly thereto. The pivot pins or other bearing structure such as a boss, extends from the outer surface of the sidewalls of the bracket to engage appropriately contoured hinge plates of a bucket. Since the load bearing structure is cantilevered from the sidewalls of the bracket, the forces are not directly transferred from the hinge plates of the work implement to the sidewalls of the bracket. Because the sidewalls of the bracket assembly serve only as support for the load bearing structure, very substantial structural members must be positioned laterally between the sidewalls to strengthen the bracket assembly. The laterally extending structure also provides support for a locking device that is centrally disposed between the sidewalls. The locking device is needed to secure the bucket to the bracket assembly. Since the locking device is offset from the connection between the bracket assembly and the bucket, the forces created during a digging operation are amplified as they are transferred from the pivot pins, through the bracket structure and to the locking device. This requires the locking device, as well as the lateral structural members, to be of very substantial size and weight to accommodate such severe loading. As a result, the entire weight if the bracket assembly and attached bucket is far greater than that of a conventional bucket. The additional weight works as a great disadvantage to the operation of a vehicle. Each pound of additional weight reduces the capacity of the bucket by a pound. Also, for each additional pound at the bucket, an additional two pounds must be added to the counterweight at the opposite end of the vehicle. Two designs of this type are disclosed in U.S. Pat. No. 3,556,323 issued on Jan. 19, 1971 to Damian M. Hermmermann and U.S. Pat. No. 4,214,840 issued on July 29, 1980 to John H. Beales.
The present invention is directed to overcoming one or more of the problems as set forth above.